Most of us are familiar with the fact that with solid objects, it is harder to start things moving than it is to keep it moving. A similar phenomenon occurs with fluids, where we use the term viscosity to indicate the frictional effects. With most fluids, keeping it stirred is easier or stays the same when compared to starting to stir it.
But there are a few classes of liquids in which the opposite happens and it actually becomes harder to keep stirring once begun. With some, applying pressure or an impact to the fluid can make it seem quite hard. Via Pharyngula, here is video of a demonstration of that effect.
The students in a research lab in the Macromolecular Science department at Case Western Reserve University (where I work) discovered a compound that had such properties. They realized that it would make a good temporary pothole filler. Potholes are the bane of existence in this part of the country where the repeated freeze-thaw cycles in winter are conducive to creating them, and the usual repairs take time to apply (disrupting traffic) and don’t last long.
These students realized that if you put the fluid into waterproof bags, the flexible bags can be simply dropped into the potholes. When cars go over the bags, the impact makes the material hard. Problem solved!