Not exactly a lollipop but it is ice on a stick. I've noticed this phenomenon for many years and often wondered what caused it. On cold mornings , even when there isn't frost on the ground, large crystals of ice grow out of small twigs. The only explanation  can think of is that the twig contacts squeezing sap out of small pores (twigs have pores I think) as the liquid squeezes out it freezes. Well not much of an explanation but its all I can think of.