The country which is in advance of the rest of the world in chemistry will also be foremost in wealth and in general prosperity. - William Ramsay.
Calcium gluconate is typically used to treat calcium deficiencies. However, when it is heated, it causes a huge expansion in the molecular structure. This results in a gray snake-like foam caused by vaporization of water and dehydration of hydroxyl groups within the compound. In less scientific terms, when heated, calcium gluconate rapidly decomposes. The reaction is as follows 2C12H22CaO14 + O2 → 22H2O + 21C + 2CaO + 3CO2