Quicksand
It was commonly believed that the behavior of quicksand was due solely to saturated or supersaturated suspensions of granules in water.  Pressure from underground sources of water would separate and suspend the granular particles, reducing the friction between them. In 2005 it was been shown that the presence of salt is important. The stability of the colloidal quicksand is changed by the presence of salt. It increases the high viscosity regions of sediment responsible for quicksand's "trapping" power. Another finding was that a human cannot be drawn into a saltwater quicksand entirely.