Why does freezing water in an ice tray only sometimes form ice cube ‘stalagmites’?

Question

[Picture](https://imgur.com/gallery/MKDz4dx)

In: Physics

Answer 1

When water gets frozen quickly in supercooled conditions sometimes the surface becomes covered save for a small hole. Water expands when it freezes, forcing the water underneath to go through the hole and freezing into this spike shape.