“A watched pot never boils” is a saying which normally means you shouldn’t spend your time worrying about lengthy processes which you can't control — or something like that. Harrison McIntyre, however, decided to take this literally, and made a pot that won’t actually boil when you watch it.
McIntyre's project, in its original iteration, uses a Raspberry Pi 3B, running facial detection to see if you’re looking in the direction of a heating element under a kettle. If it detects a face, the Pi activates an AC relay to switch power off. A “power tail” style device is implemented here in order to keep from having to get into the AC wiring itself.
One might correctly assume that with a limited field of view, all you really have to do to watch this pot (and have it boil) is look at it from one of the many non-covered areas. McIntyre considered this as well, and in his second version upgraded from a Raspberry Pi and single camera to a desktop PC with six cameras for much greater coverage. Here an Arduino Uno clone is connected to the PC, which directly activates the relay needed.
It’s an interesting experiment, seen in the video, with code available on GitHub. It’s noted that such a setup could also be used to turn the burner on when it sees a face, which could be used as a safety mechanism to make sure someone is paying attention.