Compare Pot to Hot Tub cooking
Question: What’s the difference between a boil, a rolling boil, and a simmer?
Answer: A chef friend of mine explains it this way: Imagine the pot is a hot tub and the bubbles are (scantily clad... highly attractive) people.
A simmer is when the water is warm and the bubbles are just hanging out around the sides of the tub. A boil is when the water is so hot that people are kind of jumping around the tub. A rolling boil is when the people are trying to leap out of the tub for fear of being burned alive.
I think that explains it perfectly!