The idea is that the pump squirts a stream of water droplets on a regular basis which are synchronised with the mains power frequency. A stroboscope is then shone on the stream of droplets which depending on the flash frequency will freeze or slow down the motion of the droplets.
Below is a video of a similar apparatus at one of MIT's museums:
After more sleuthing on the internet I found a web page owned by Professor Derin A. Sherman he has a demonstration using the same principles.
Here is the video from Professor Derin's lab demonstration:
My Lab Demo:
Initially I was unsure as to what sort of pump would be available here in New Zealand however that was short lived. Espresso coffee machines use a oscillatory piston pump to achieve the 10 to 15 bar extraction pressure required. My mate Hamish aka b45h4 has a dead coffee machine sitting in his garage just begging to be "hacked" :D
Thats all for now - check back in a couple of days for pics and videos.