At some point in our lives, we all have watched pots of water boiling.

Big bubbles will rise from the bottom of the pot. Big, not pinhead size.

If it's bubbling a lot at the sides of the pot, too, this is what's called a rolling boil. You can't stir down a rolling boil, which means if you take a wooden spoon and stir around the pot in a circular motion, the bubbles will keep coming up. Small bubbles can be stirred down - made to disappear - this way.

One of the oldest pieces of cooking advice: Put on a pot of water to boil as soon as you walk in the door. Turn the heat up as high as it will go to achieve boiling and salt the water if you are going to cook pasta. But why?

Many think that adding salt makes the water hotter and so cook the pasta faster.

Technically, adding salt to water will make it boil at a higher temperature. But to raise the boiling point even one degree, you would have to add about 225 grams of salt (at high altitudes); or more, 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. This would mean that adding 20 grams of salt to a standard pot of 5 litres of water raises the boiling temperature from 100°C to 100.04°C.

Let us look at why this is so. When a liquid boils, what is actually happening is that the vapour pressure of the liquid equals the atmospheric pressure, so that bubbles of the vapour appear in the liquid.

For pure water at standard pressure (1 atmosphere), the boiling point occurs at 100°C. 

If we start with just barely boiling water and add some salt, the water will stop boiling. The salt has lowered the vapour pressure of the solution. To increase the pressure we need to add heat. To add heat, we increase the temperature.

So why do we need to add salt to the water? Since salt is a primitive taste sensation, we probably add salt to make the food taste better.

Water boils faster on an electric element than it does over gas flames. Some gas flames may not turn down low enough to achieve a very low simmer. A flat iron plate, called a flame diffuser, can sit directly over the fire. With a pan on top of it, you can achieve lower heats for delicate sauces.

The more water in a pot, the more slowly it will boil. Volume matters on this one. And don't think you can cook pasta faster by cooking it in a little water. Italians say pasta should have room "to swim." It needs room to roll around.

The biggest problem with cooking pasta is keeping it from sticking together. Most tricks don't do much good either. The fact is pasta is starchy and will stick a little, no matter what. Contrary to popular belief, do not add oil to the water, that simply coats the pasta and sauces slip right off. Also, do not rinse the cooked pasta, rinsing eliminates the starch preventing sauces from clinging to the pasta.

Ciao!