system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When I'm cooking, why does stirring the pot slow the onset of boiling?

And likewise, once something is already boiling over, why does blowing on it make it stop?

From what little I remember of the high school physics class I nearly failed more than half a decade ago, it seems like stirring or blowing would be adding kinetic energy, which should increase/encourage the boil, shouldn't it?
gpt
Yes, stirring adds kinetic energy, but nowhere near enough to make an appreciable difference in temperature.  Water takes a LOT of energy to heat up, more than you would ever be able to achieve with a spoon.

As for why it slows the onset of boiling, it doesn't really, it just makes it look that way.  When you have a pot on the stove, the water on the bottom is very hot compared to the water at the top.  The water on the bottom will start to heat up and boil, but it immediately cools when it rises up into the higher water.  That's why in early boiling you see little bubbles come up off the bottom of the pan and then immediately disappear.  When you stir the water, you are equalizing the temperature inside of the pot, so instead of warm water with a very hot bottom, you now have a pot of water that's evenly warmer.  You won't see the bottom "boiling" but you're not really changing the time it takes to get the whole pot boiling by all that much.