Have you ever experienced the phenomenon of superheating
water in the microwave? Superheating is what happens when water is heated past its boiling point, yet doesn't form the bubbles we associate with boiling. Superheated water is dangerous because it looks like it's cooler than boiling, yet may actually be several degrees hotter! Also, when the superheated water is disturbed, as by bumping the container, stirring the water or adding something to it, the water may suddenly boil or vaporize into burning steam.
Minimize the Risk of Superheating
You can lessen the chance of superheating your water by using the minimum cooking time for water or by providing starting bubbles that will allow the water to boil more freely. These bubbles can be introduced by something as simple as using aerated water from the tap. Glassware that is slightly rough or scratched is less likely to superheat water, too.
The Myth About Superheating Water
Some people believe only pure water will superheat. This is not true. Water with impurities, such as tap water, can superheat. It is simply less likely to superheat because tap water usually comes straight from the tap and contains a lot of air. Tap water that has been sitting on the counter for a while can superheat. Many homogenous liquids can superheat, including coffee and tea. Similarly, it is untrue that you can only superheat water in a microwave. It is true that it's easiest to superheat water in a microwave, particularly one that does not rotate the food, but you can superheat water on the stove or other heat source.
Share Your Experience
Have you experienced superheating? Feel free to share your experience, particularly if you superheated a liquid other than pure water.