weird patterns in solutions
Those rippling transparent patterns are caused by the variations in refractive index, which in turn are caused by the variations in concentration of the solute. As soon as the dissolution and mixing is over, and the solution is uniform again, the patterns are gone. I don't know the English word for it, or whether there is one; "Schlieren" seems to be much more general.

It's a physical phenomenon indeed, but chemists might be more used to seeing it.

You may observe a remotely similar pattern around a heated object in the air (see "heat haze"). In that case, it is caused by the variations of temperature and not concentration.