Why does a tower break the way it does when demolished?

When a tower/chimney/etc is demolished, the explosives are often placed at the bottom of the tower, sometimes only at one side to control the direction in which it will fall. Almost always however the following can be observed: As the tower comes down, it first maintain its straight structure. But some time during the fall it breaky up into two or more pieces which will then continue falling as separate bodies.

I would like to know what is the scientific explanation behind that and how can one calculate beforehand how the tower is going to break up. I am aware that this may depend on certain factors such as the material that the tower is made of or even the wind. But I am interested in the basic phenomenon and how to get a calculatory handle on it, so simplifying assumptions can be made (homogenious material, no wind, ...)

Thanks in advance!