Why do really cold objects evaporate really quick? So I saw a video of LNG (liquid natural gas) and when it got in contact with water, which was room temp the LNG evaporated instantly...why? 
Ice takes a while to evaporate like a sec even when hot water is dumped...why do really “cold” liquids evaporate super quick. Is there a name to this phenomenon? 
If you can dumb down your answer that would be great...I am only in 9th grade. 
 A: The “boiling point” of LNG is -162°C (-259°F), so putting it in touch with even cool water (10C) is a 170C temperature difference. 
That’s like putting water on a 270C (520F) griddle. The water boils quickly. 
To add to the effect, water requires an unusually large amount of energy to boil a cc. LNG needs a lots less to boil a cc, so heat transfer can boil it fast. 
But the biggest effect is the huge temperature difference. The world looks HOT to cryogenic liquids like LNG. 
A: I'll add to the answers above, (though @BobJacobson touched on this).  Water has a high heat capacity.   Air is very disburse and by contact area, a very very low heat capacity.  (Heat capacity is usually measured by mass, not contact area, but I think contact area is important in relation to this question)
Water is able to transfer heat to the LNG and make it boil much faster than it boils in air.    The same kind of thing happens to us.   A person can sit in a 212 degree sauna for a period of time without being burned.   212 is hotter than most saunas are set, but that temperature is manageable for a healthy person for a few minutes if it's dry air.    But put your hand in 212 degree water and you have a first degree burn in 2 seconds.   Water, even cold water is able to transfer a lot of heat into LNG or onto a person's skin than air, and as a result, it boils very quickly in contact with water, even what we consider cold water.  
A: Temperature can be viewed as the intensity of the movement of the molules. LNG molecule don't move much, while molecules in ice move significantly more. If the colder molecules get in contact with molecules with higher temperature they transfer the more energy the larger the energy difference is between them. For the LNG this means that a very large amount of molecules reach above the boiling point very quickly, while the energy transfer between ice and water is taking place much slower.
