Just pour a 1/4" of water in a shallow glass baking dish (preferably with a smooth bottom) and add a teaspoon of vegetable oil (or whatever). Then take a toothpick and distribute the veggie oil however you like.
It works best with a macro lens to get in tight on a single area of small bubbles. The most challenging part is getting the focus just right.
I use a glass top table with the CD placed 6" to 8" under the baking dish and a light directed at the CD. Move the CD around for different effects.
One thing I've noticed is that the image I see in the viewer seldom resembles what comes out in processing. The color spectrum seen by the camera is usually different. You can also play around with different PP effects (white balance adjustments, saturation, etc). Like I said, it gets addictive.