For the Long Night of Science in Erlangen, I have prepared an experiment where light is being bend by propagating inside a gradient refractive index media. Here is the recipe:
1. Prepare saturated sugar solution:
Dissolve 6 kg of sugar in 3 l of water => Will produce more than 7 liters of sugar solution (keep in mind for beaker size). Fill beaker with water, use magnetic stirrer and heat solution to about 50 °C. Pour in sugar, small amounts at a time. Try to avoid having a layer of sugar on the bottom, this will burn and produce caramel (which might taste good but is not helpful here).
Fill an empty fish tank with the saturated sugar solution. Use a tube to fill it carefully with water (maybe 20 or 25 liters, about 5 times the sugar solution) on top of the sugar solution. Try to avoid that the solutions mix. Diffusion will produce the sugar concentration gradient within a couple of hours. Shine with a laser from the side to see several bounces from the bottom glass.