road boil

the surface of a travelled portion of a highway that becomes liquified underneath it and the pavement, gravel, slurry or mud pushes upward

a road boil appears on a road in the spring. It is believed to be caused from winter months springs located under roads do not completely freeze but the surrounding area does, when traffic drives over the road, it forces the moisture to the top so it has the appearance of a boil or bubble. There is one just below MacDonald's hill!