When I put a tea bag into a cup of water I've heated in the microwave oven, it causes it to boil, why?

Answer 1

This phenomenon is called "Super-Heating" In a microwave, sometimes water gets hotter than the boiling point without the bubbling we have come to expect. When you break the surface of the Super Heated water with a tea bag or spoon, it causes the water to "explode" This can be very dangerous. People have been seriously burned from this Super Heated water exploding when its not expected.

Answer 2

I agree with the above answers. I've learned to avoid that by putting hot water in my mug, then adding the tea bag, then microwave on high for 1 min. & 5 seconds. Works great. Don't squeeze the bag when removing from the cup, or the tea will be bitter tasting

Answer 3

Not sure if this is what you're asking, but you may be "superheating" your water... when you take it out of the microwave the water will be calm, but it will begin to bubble if you touch the water with something (introducing "nucleation sites").

It is possible for the water to bubble violently if *greatly* superheated, but that's very hard to do.. mild superheating is much easier (and less eventful) and may easily happen while heating water in a microwave --particularly in a clean glass container. Try heating the water for a shorter time if you don't want that to happen.

Loads more info and explanations here:
http://www.google.com/search?sourceid=navclient&aq=t&ie=UTF-8&rls=GGLC,GGLC:1969-53,GGLC:en&q=superheat+water+microwave


Diane B.