One of the most basic things my mother taught me is how when cooking, the fire has to be lowered as soon as the liquid boils.

Mother dear talking: as soon as water or any cooking liquid has reached its boiling point, lowering the flame does not matter. It will be as effective. Doing so saves on energy and money.

There are just a few exceptions - one of them is when cooking pasta, th water has to be kept on a rolling boil to prevent it from sticking together (no, I don't add oil to my boiling water) and from getting soggy.