[dba-Tech] "Intelligent" candles

My friend Murph has recently visited a couple of times, on each occasion
(being one of those rare old-school gentlemen) bringing a small gift of
insignificant cost, but a gesture in thanks for the meal I had prepared,
the gift being a candle in a glass jar suitable for potables once fully
burned and cleaned.

The interesting part to me is the nature of the wax, and its possible
contents that make it work. In its initial state, the wax is a pale grey
non-colour. But when you light it, the candle immediately turns its wax
green, then blue, then purple, then red (the sequence might be incorrect),
and as long as left burning, cycles through the colour-states every 30
seconds or so.

Quite by accident I discovered that it's not even necessary to light said
candle: the warmth of your hand is enough to begin the cycle.

I have no idea how this phenomenon is achieved, but it is very cool,
assuming that you're the sort of person who appreciates candles.

There are NO electronics involved. It's just wax in a glass and a wick. But
obviously something has been added to the wax.

Does anyone have an idea how this candle works, and according to what
principles?

A.