What we did was we covered a speaker in cling film and poured water into the dip in the speaker cone.
When we turned on the speaker and the water started jumping.
We played around with the hertz and found that the lower frequencies had a greater effect on the water.
We then put a mix of water and cornflour on the speaker. The result was different to the water on its own.
The thing about cornflour and water is, is that it's a non-Newtonian fluid.
That basically means that it's impossible to splash it if you punch it.
The cornflour and water didn't splash up like the water.
Instead, it rippled and changed shape.
This experiment along with the experiment to try to break a glass using sound waves prove that sound travels in pressure waves and these waves can push and possibly break things.