Four snapshots from a movie of the collapse of an initially large sphere with uniform (low) density of stars with small random motions (courtesy Anatoly Klypin, NMSU). The collapse accelerates as it proceeds, and inhomogeneities grow. Just before first "crunch" there are several large regions. At this point, the gravitational potential is both deep and inhomogeneous and changing rapidly. Each star experiences this "chaotic" gravitational landscape, its energy is changed, and it emerges on a different orbit. There is a first "rebound" as the stars emerge from the first collapse (it is a collisionless system, so none collide at the bottom). Some stars are lost to the system, others go up high, yet others stay close to the center. There is a second rebound, and subsequent oscillations which quickly become less distinct. The system settles down with an approximate R1/4 projected surface density.
You can view the full movie here (65 Mb .mov format). Many thanks to Anatoly Klypin, who created this movie for us.