Bubble mix doesn't last long in the hands of a child. Create a bubble station to provide a solution. This is so clever! / Only clever until the solution falls below the top of the bubble wand loop - then it doesn't work.
Child's Play: The Art of Toy Rotation- a great article on the toy overload problem. I would add a permanent group of toys (ones that a child is attached to) and the rest would go on rotation list and out of sight.