There are almost always guidelines on pasta packages for the amount of water you should use when boiling.  Sometimes I'd like to use a pot that's on the smaller side, and that got me wondering; what actually happens to pasta if you use too little water (assuming it's at least fully submerged)? 
See:    What is the correct water to pasta ratio? How much water to put in my pasta pot?   Short answer:  if you stir once or twice at the beginning to prevent sticking, and all of the pasta is submerged, you can very successfully make pasta in a reasonably small quantity of water.  Here is a direct link to the Serious Eats article both of the answers above cite. 