A while ago I was cooking rice, and I noticed a recurring pattern of creation and destruction of bubbles.
It seemed like the bubble-layer would increase in height, until it 'popped', and the layer height severely decreased, see the images below, which are snips taken shortly after each other. and the Youtube video. My hypothesis is that the layer would rise to the lid, and would then squish the bubbles until destruction. But I don't have any knowledge on starchy bubble dynamics to back this up.
I don't think this is a duplicate of this question, as it is indicated that this could be linked to the starch in the water, where the other question only deals with water (without any other ingredients).