I have a rather stubborn active to get into solution. It was spinning in a raft of dry powder on the top of the water while I watched intently (to make sure it WAS slowly going into solution and that the spinning didn't stop). When ever I looked away I saw a ghostly spiral galaxy spinning the opposite direction around anything I looked at. It was dizzy, but fun to play with.
Edit: But, argh! Now my silver-dollar sized sunburn is itching!