What Causes the Tread on Your Tyre to Separate?

Did you know that it is possible for the tread pattern on your car's tyre to actually separate from the rest of the cover and fall away? As scary as the thought is, this type of event does happen from time to time, and it's important to understand why that should happen and know what to do in order to prevent it. So, what can cause the rubber to separate in this way?