Bring the maple syrup to a boil, and allow to caramelize for about 8-10 minutes. Do not stir. You need to use your intuition here, so don’t stress out! At first, the syrup will have a lot of small, almost foamy bubbles. As it starts to caramelize, it will slow down and the bubbles will get thick and large. You will know it is just about done when the aroma goes from sweet to a dark, deep maple smell.