Why can coffee and water explode in a microwave?!
Answers: The other day I put two-thirds of a cup of luke warm coffee in our microwave, and I wasn't really awake, so I set it for 60 seconds. At 50 seconds, we heard a very loud report (pop), and I saw a bright light flash in the microwave. It stopped the microwave temporarily. The coffee had exploded all over the inside of the microwave. A couple of years ago I received an email that told me water can explode when put in a microwave. I was told by my daughter's boyfriend that one can put a toothpick in the coffee or water, and it won't explode, but I have no idea if that's true because I've only had the coffee explode once. There was about an eighth of a cup of coffee left, and I added more luke warm coffee with some liquid creamer; it was still extremely hot. I don't understand why it isn't anounced that this can happen...
I think it has something to do with the surface tension of the drink (any drink will do it, doesn't really matter what it is). If the drink can't bubble when it boils to regulate the temperature, it will superheat, and won't look any different, so you can't tell it's boiling. If the surface tension is released (usually when the cup is moved) all the energy in the drink that would normally be released by boiling releases at once, which we see as an explosion. If you put something in the cup that breaks the surface tension (I heard a popsicle stick, because it's longer) then the bubbles have an escape route, and the drink won't superheat. I don't know what would cause the flash of light though.
yes, water heated in the microwave can become super heated, but I thought it was pretty rare. I guess the situation has to be just right.
did the cup have metal trim on it?