The old microwave took about three minutes to bring a cup of water to boil.

I heated water--was it to make coffee for my sister? We were distracted, and I didn't take the cup out right away. So, when I returned to the microwave, I figured it had cooled some. I'd bring it back to boiling. Without opening the door to check, I turned the switch and watched through the tinted window. 15 seconds passed, 30. The surface of the water was smooth as glass. A minute. A minute and a half. Two minutes. I knew something was unusual. The water had not cooled that long, and here it was nearly 3 more minutes, and it was not boiling, not even rippling.

I turned it off. I opened the door and as I reached in, I changed my mind and stepped back.

The water erupted into boiling fury, shooting and spitting everywhere. Only half the water remained in the cup.

Smooth surfaces can be deceptive.