That is to say that as the water is heated and starts turning to steam, the density decreases sending the hottest water and steam to the top of the furnace tubes.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request. ### Instruction: List the MITRE techniques contained in the text. ### Input: That is to say that as the water is heated and starts turning to steam, the density decreases sending the hottest water and steam to the top of the furnace tubes. ### Response: .