So all of a sudden, the star, trying to hold itself up, runs out of fuel. The star collapses in on itself, and material rebounds off of the central core on a tremendous explosion. When a nearby star goes supernova, it will shine so brightly that we can see it during daylight. In the core, the force of gravity is sufficient to overcome the electron degeneracy pressure, and the electrons are driven into the atomic nuclei. Each electron combines with a proton, producing a massive sphere of neutrons.
Most towns are larger than that.
Black holes You might guess that with sufficient mass, even the neutron degeneracy pressure holding up a neutron star can be overcome. When this happens, the star collapses in on itself completely. It becomes so dense, only objects travelling faster than the speed of light could escape its gravity. It's a common misconception that all stars eventually become black holes. Actually, most stars will eventually become white dwarfs.