It may not work for a pot or a kettle, but thanks to some operating systems giving the topmost focused window process a higher priority, it does work for computers.

This will only really work If the process is graphically intensive and is doing an awful lot of computation eg.

It can be worthwhile just clicking on that window to make it focused and watching time pass by. Hint. Open a web page and do some practical research, just keep bringing that process window back to the top and clicking on it if it goes away because you have clicked on something in the web page.

So next time someone says “A watched kettle never boils”, you have the counter argument.