A similar process occurs intentionally in the case of a radio wave generator. Some of the output from an amplifier is fed back into its own input. If the signal is fed back such that it is "in phase" - ie: the peaks and troughs of the incoming signal correspond exactly with those of the fed-back signal - oscillation will occur. This is called positive feedback.
Negative feedback (where the fed-back signal and the input are not in phase) is also used in situations where high gain (ie good amplification) is wanted but without the unwanted tendancy for the circuit to go into spontaneous oscillation.