How might a candle drown in its own wax?

A common problem with burning candles is when the candle burns down inside itself and drowns in its own wax. There are a number of reasons for this -

If the candle is only burned for short periods and extinguished before forming a wick pool then wax that should have been used up in previous burnings will melt and drown the wick.

If the wick has curled over into its own wick pool and put itself out, then the wax will set over most of the wick.

The candle wick is far too small.