What happens to boiled pasta if you use too little water?
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.