Heating water in the microwave

[HenrikWL]

I see this advice a lot, but have yet to see the warning I'm about to give. This either means that this is common knowledge, or that people genuninely are not aware of this. Either way, I feel I have to post this.

If you heat water in the microwave, don't let reach boiling point. Ever. And if you do, leave it alone for 5-10 minutes. At least. Without so much as touching it.

The reason for this is because of the way microwave heating works. The body of water is not heated evenly - it has hotter and colder areas. Now, if the water was 100% pure and free of contamination this would not be a problem, but no water is that pure. Around these impurities may form "bubbles" of water that are actually hotter than boiling temperature. These bubbles are highly unstable, and may in fact explode(!) at the slightest provocation, splashing scolding water out of the container.

Now, I guess noone here likes to shave with boiling hot lather () so I guess this would really only be a problem if one made a mistake or something, but I reckon the warning is still valid.

One may argue that compared to the dangers of scraping ridiculously sharp knives across one's face, heating water in the microwave might seem insignificant, but it's always better to be safe than sorry.