So this is what happens when you mix salts of different metals (Lithium, Strontium, Sodium, Copper, and Potassium) into methanol and then light that sucker.
Pretty colours is what.
Each metal has a different configuration of electrons orbiting in the atom. When the different atoms get energy from the heat, the electrons in the different metals will be excited by a different amount. When they de-excite they release that energy as light. Different metals release different eneriges. Different energies is different colours. The more energy, the violeter the light.
Using different metal salts is also how fireworks do the thing.
See the streetlight yellow in the Sodium (Na)? Well that’s because we use sodium lamps in streetlights