It turns out that trees can actually explode when temperatures drop.

Tree sap is mostly water with sugars and minerals, and like many liquids, it expands when it freezes. Gradual freezes usually don’t harm trees — even if it gradually cools to subzero — but plunging temperature swings cause uneven freezing and internal pressure. This stress can crack the bark and wood, producing what sounds like a loud pop.

A tree-mendous freeze. Forecasters are warning that expected subzero temperatures could cause trees to explode as a brutal cold snap is expected to wallop most of the country in the coming days. Trees may split and burst across the Midwest and Northern Plains Friday and Saturday as a bitter Arctic blast from Canada sends temperatures plunging to roughly 20 degrees below zero,