Putting the pasta in enough water
Pasta is cooked 1:10 (100g spaghetti - 1l water). The starch swells during cooking, so spaghetti need a lot of space. If the pot or the amount of water is too small, the pasta will stick together. Boil the water in a pot, salt and put the spaghetti in it. The noodles will slowly slide into the water.