This sounds like statistical mechanics thinking to me. At the macro-level, water that is at freezing temperature but that has not frozen yet will appear liquid.

This sounds like statistical mechanics thinking to me. At the macro-level, water that is at freezing temperature but that has not frozen yet will appear liquid. However, what's happening at the micro level in the fluid is that small pockets of the water are switching back and forth from frozen to liquid as their bonds tighten up from loss of thermal energy. There's still enough energy in regions of the liquid mass such that these isolated crystals may not be crystals for very long, because the thermal energy transfers from hotter to colder regions, but because the whole mass is bleeding energy into an external system it will eventually reach a tipping point where larger crystals can persist for longer, until eventually the water turns into ice.