Osmosis experiment (Raisins in water with Sucrose solution)?

Osmosis occurs on a concentration gradient. Sucrose molecules in areas of high (sucrose) concentration will migrate to areas of low concentration until an equilibrium is met (the concentration is the same throughout). At low concentrations of glucose (10%, 20% and 30%), there are more sugar molecules in the raisin than in the solution. As a result, water travels from the solution into the raisin (in order to maintain a constant concentration throughout). At 40% glucose concentration, there appears to be more sugar in the solution than in the raisin, therefore water travels out of the raisin and into the solution to reach this equilibrium.

The answer is indeed equlibrium, but we must count the movement of water AND of sucrose. A raisin has very little water in it; it is, after all, a dried grape. Therefore, it will take on water until equlibrium is reached at the 30% stage, and so it weights more in each successive concentration. However, once the water reaches equilibrium and the sucrose is increased past the level in the raisin, the sucrose will begin to diffuse out of the raisin into the solution, which apparently happens at 40%. The loss of sucrose as it diffused from the raisin into the solution accounts for the loss of weight of the raisin.