and yet more from the Sober Husband

It is one of the Occasional Features of this blog that the readers' questions are put to the Sober Husband. Completely coincidentally the Drunken Housewife got very angry, in an unrelated matter, after soliciting questions, and consequently the Sober Husband has, in a conciliatory manner, been working extra hard to get those questions answered. Herewith Another Question Answered By The Sober Husband, this one going out to one of our delightful Texas correspondents, Texzmissy:

My question for the Sober Husband: True or false: You can microwave a cup of water and when you take it out of the microwave, if you are not careful, the water can more or less "explode" and you can get your face burnt with the presumably boiling water.

I say no, but my daughter insists that her science teacher says it's possible. Of course, it could be that the teacher said it was NOT possible, or only theoretically possible, and she wasn't listening, but I'd still like to know.

My first response is that it seems ironic when a science teacher is cited as an authority, especially on a subject that is so easy to explore experimentally. If I were the teacher, I would say: Try and see.

Anyway, I've tried. I have certainly been able to generate fairly violent splatters from a mug of hot water.

The idea is that while boiling requires high temperatures, it also requires sites for "nucleation" of the gas phase, like particles suspended in the water, or rough structures on the surface of the container. If the water is clean and the container is large enough, I think the water may well become "superheated" in the center (hotter than its boiling point) while still not converting into gas. Then when some nucleating material is introduced, like a teabag, there can be lots of thermal energy ready to generate a lot of steam in a short time.

I suspect a lot depends on the oven, the container, the heating time, and the stillness of the water. First, put the container in the oven, wait five minutes for the water to become absolutely calm, and then see how long you have to heat it before it starts boiling. Then, put the exact same amount and temperature of water in the same container in the exact same part of the oven, let it become calm, and heat it for ten seconds less. Leave it in the oven, but drop in a spoonful of sugar.

Let us know what happens.

Please perform this experiment at your own risk. The Drunken Housewife is not responsible for any injuries or damages sustained in the pursuit of science.