A rock with a crack in it that has filled with water, frozen, thawed and then refrozen until it has broken is one example of frost wedging. Water expands when frozen.
Most rocks and stone formations are riddled with tiny cracks, fissures and holes naturally. Rainfall trickles into these natural openings. If the water does not evaporate, it sits in the opening and when the temperature drops low enough, the water freezes and as it freezes, the particles expand, pushing the crack or fissure open wider. Over time, the process is repeated until the rock breaks apart. Frost wedging is an example of physical weathering, and it is usually a slow process that can speed up in more extreme climates.
The process of water expanding as it freezes can be seen with simple ice cube trays. Fill the ice cube trays with water and put them in the freezer making sure to mark where the water line is. Once they are frozen, remove them, and note that the water has expanded over the original line.
Other types of physical weathering include erosion, oxidation and thermal expansion. The process of frost wedging has nothing to do with cooking, frosting cakes, baking or food.