Why does it take longer to boil water in a new saucepan than in a saucepan already in use?

As soon as any of the salt dissolves in the water, the boiling point of

the water will begin to rise -- by about one half degree Celsius for every 58 grams

of salt dissolved per kilogram of water.

In fact, any non-volatile soluble

substance will raise the boiling point of water. That is why antifreeze (ethylene glycol)

provides boiling protection in winter as it simultaneously provides freezing

protection in the summer.