It does sound like you are lagging out. When this happens and you hold down tab, does it show the other players? What does it show your ping is?
open command (~) and try:
/cg_lagometer 1
that will tell you when you are lagging out, among other things.
When you lose connection with the server, your game client keeps estimating where you would be on the map based on your continued movement, movement which the server never recieves. When the connection to the server restores, your game client puts you back to where the server says you are, hence the "snap".
I have this problem when my wireless connection goes to crap, that could be the problem too.