The latest installment of Veritasium is all about the "Pyro-Board." This snazzy contraption is a mesmerizing, planar take on the Rubens' tube – a perforated tube of gas – hooked up to a gas jet and a speaker – that can turn music into beautifully patterned, leaping flicks of fire.
The video demonstrates how gas inside the board can vibrate and resonate to form standing waves, which give rise to the flame patterns that kick off around the 3:38 mark:
The pressure variations due to the sound waves affect the flow rate of flammable gas from the holes in the Pyro Board and therefore affect the height and colour of flames. This is interesting for visualizing standing wave patterns and simply awesome to watch when put to music.
Complement with this video of the Chladni plate experiment, which also uses sound to give rise to standing wave patterns.