The superheating of distilled water in microwave oven

[superkaho]

As we know, the heating principle of microwave oven is by the vibration of water molecules inside the food. However, it is reminded that a cup of water should not be heated by the oven, otherwise, water would be overheating but not boils. Once it was stimulated, it boils.

From the prespective of chemistry, can anyone explain me the reason? thanks in advance.

 

[dawin]

It's my understanding that its typically caused by a lack of nucleation sites on which bubbles form and rise. That and there isn't a lot of convection going on due to a different heat gradient than that encountered with a stove, for example.

Water superheats in a glass (smoother than a pot) with no nucleation sites for bubbles to form, spoon or something else breaks surface tension and introduces nucleation spot causing steam bubble to exit violently.

Could be wrong, wouldn't be the first time.