Bon Appetit shows us how to better use our pans:
Here's a simple test: Fill your pot or pan with a few inches of water and bring to a boil on high heat. Hot spots are the places where you will see rapid bubbling. The cold spots are the places where you will see few bubbles, or none at all. In the picture above, I boiled rice to better illustrate the hot and cold spots. The ring of bubbles are where the flames from the gas burner contact the pan. The centre of the pan is over the cap of the burner, and not in contact with any flame at all, and therefore a cold spot.
The hot and cold spots, the article says, are a function of the materials the pan is made of, as well as your heat source. Knowing which spots get hot quickly and which never heat up well enough can help you move the food around in the pan like a pro so that everything cooks up evenly -- and you avoid those dreaded burnt spots.
Never Burn or Crust Your Stainless Steel Pans Again [Bon Appetit]