The Faraday Wave Experiment
You fill a container with a liquid and shake it vertically at a fixed frequency and amplitude. That is the experiment M. Faraday presented in an appendix to an article in the Philosophical Transactions of the Royal Society London in 1831 [5].
In this article "on a peculiar class of acoustical Figures" Faraday writes about how, by choosing the right combination of liquid, frequency, and amplitude, very beautiful square patterns of standing waves can be seen on the surface of the liquid.
The experiments I have done with this set-up were to trace small particles floating on the surface, and thus measure diffusion on the surface waves. When you look at the tracks of the particles, they appear, in striking contrast to the surface waves, to be quite irregular and random. It would be interesting to understand how this random motion on the surface can be induced by the ordered motion in the bulk indicated by the wave patterns.