We have a pot that bears watching. As soon as the water heats up a bit, it starts vibrating, albeit at a low frequency. The pot rocks back and forth and it rotates like a clock.  To stop this progression, I insert a spice jar of appropriate height under the handle.

I could not resist photographing the standing wave of water on its way to a vigorous boil.

Standing Wave

Contrary to folk wisdom, my watched pot did boil eventually. I did have to use the spice-jar leveler to quell the waves and prevent the water from spilling.