I get them in my car which has done 173,000k's on original suspension...
It sounds as if the springs are popping out of the cups, but I don't know if this is possible, all I know is, one i went around a corner, the car lifted, the clunk happened, I felt the rear still raised... When I turned the car at the next corner it seated back down again.
Still, I am sure there are others on this board who will help ya!