Steam explosion and how to prevent it while cooking I hope this is not off-topic. I have googled for background info but didn't find much on cause and prevention. So the question to some experts.
The following accident just happened. I would like to know (or confirm) what happened and especially would like to know how this can be prevented.
Setup. This is real life. We do this several times a week as addon for pet food:
I cook chicken in a pot 8 inch diameter and about 6 inch high. The chicken is cut in small pieces 1 inch size. This fills more than half of the pot. It has a lid.
It is covered with water. Now it needs to cook 1.5h at low heat. There has never been a problem until today.
There were about 30 min left when I noticed that it didn't visually boil anymore. It usually does that at the setting. I was confused and turned up the heat to middle (5 of 9). Nothing happened after 10-20 sec. After this much time it starts boiling immediately when increasing the heat. So I turned to max of the stove (9 of 9). Now I got more puzzled and after waiting another 10 sec where nothing happened I wanted to turn down the heat and take a closer look inside the pot.
That was the moment when everything exploded. The explosion was so strong that the lid hit the fume hood above the stove. I was hit by the boiling water and got blisters from the burns. The water and chicken were distributed everywhere.
Now I assume that somehow the steam was collecting beneath the chicken. But how could that be. It was boiling in the beginning and the steam was able to come out. How come it suddenly after so much time exploded?
I looked for steam explosions and read if there are no "steam seeds" (translation from german, don't know if this is the right term) where the steam can develop on it could explode once it got hotter than boiling temp and suddenly went to steam. But the chicken is inside the pot. So that should serve as a steam seed?
And the question I am most interested in: How to prevent this in the future?
I have been cooking for decades and it never happened. But I have seen a similar effect in reheating a chicken soup (with large chicken legs). On reheating it sometimes bumped up the legs from small explosions. But never that fierce.
Update:
It is a normal pot with a lid on it and not a pressure cooker
 A: It is not clear if you used a pressure cooker or not. If it was a pressure cooker, there could be a problem with the safety valve or other problems (read safety tips for pressure cookers). If it was not a pressure cooker, your description still suggests there was high pressure under the lid (as the water was not boiling, and the lid eventually flew up). Probably the lid got stuck in the pan. For example, because the thermal expansion of the lid was greater than that of the top of the pan.
As for prevention, if it is a pressure cooker, read safety tips (there are too many of them to provide here). If it is not a pressure cooker, maybe you should not close the pan tightly.
A: The phenomenon, highly improbable as it is in your circumstances, is called Superheating:

In physics, superheating (sometimes referred to as boiling
retardation, or boiling delay) is the phenomenon in which a liquid is
heated to a temperature higher than its boiling point, without
boiling.

As it goes past its boiling point, at some point a violent boiling eruption occurs.
The phenomenon usually occurs in very pure liquids and near-perfect containers but it your case it did occur once.
Using so-called 'boiling stones', sharp edged pebble is a method lab chemists use to reduce the risk of superheating.
A: What you experienced is called a superheat vapor explosion. It occurs when there are no nucleation sites at which the phase change from liquid to vapor can be triggered. These are the "seeds" mentioned in the German paper.
In kitchen pots containing water, the seed sites are scratches or pits in the pot surface which are microscopic in size and which contain tiny amounts of trapped air. As they trigger boiling, the air is slowly lost from them with the departing vapor bubbles and eventually the sites become inactive. This allows the water temperature to climb above the boiling point, and if the pot is not disturbed in any way this superheat condition can be significant.
While being superheated, the water is being loaded with stored heat energy, and then when random molecular movement in the liquid produces a tiny void in the liquid by statistical chance, that void then furnishes the necessary seed and all the superheated water explodes into vapor in the same instant (i.e., the heat of vaporization is furnished by the superheat enthalpy) producing a violent geyser of hot water and steam that shoots out of the pan.
When this happens in a heated test tube in a lab, the resulting explosion will shoot the entire contents of the test tube right into your face! This is called bump boiling.  To prevent superheating, the chemist will drop a small chunk of disposable, inert porous ceramic called a boiling chip into the test tube. The chip is chock-full of cervices full of air and furnishes plenty of nucleation sites.
HP thermal inkjet printheads use this principle to drive jets of ink out of the printhead nozzles with tiny superheat vapor explosions triggered directly in the ink. In this case, the presence of nucleation sites on the surfaces of the heater elements that superheat the ink is to be strenuously avoided, and the heating rate necessary to "outrun" most of those sites is about 3 million degrees C per second.
