Molotov cocktails were efficient when used from above, because WW2 tanks were not sealed, and burning liquids went inside the vehicle, which itself was full of oil, gasoline vapors and explosives. The heat in itself was sometime sufficient to ignite the shells or their propellant. But of course, it is using flammable products not available in bronze, or even iron age, not speaking of those built by Frederic Joliot-Curie as can be seen in 'Is Paris burning' movie: a chemistry nobel prize with access to one of the worlds most advanced lab, he made truly efficient homemade weapons.