Why does a beer bottle foam up after a sudden impact on its mouth?

Movie for the APS / DFD Gallery of Fluid Motion 2013. From the paper \“Why does a beer bottle foam up after a sudden impact on its mouth?,\“ by Javier Rodríguez-Rodríguez, Almudena Casado, Daniel Fuster (Submitted on 14 Oct 2013) Abstract: \“A sudden vertical impact on the mouth of a beer bottle generates a compression wave that propagates through the glass towards the bottom. When this wave reaches the base of the bottle, it is transmitted to the liquid as an expansion wave tha