Difference between 99℃ and 100℃

When boiling an object, there is a big difference in how the heat enters the food at 99°C and 100°C (boiling state).

The difference is whether or not the liquid is convecting.
To give an easy-to-understand example, if you stay still when you take a hot bath, you won't feel as hot as you did at first. This is because the temperature of the hot water around the body has dropped. Therefore, when you move in hot water, you feel hot again.

Between 99°C and 100°C (convection occurs due to boiling), there is a difference in the way heat enters by more than 100 times.

Therefore, when boiling pasta, let the water come to a boil before boiling.