What is the meaning of "v'Ha'amideha Al Gechaleha Rekah"?
Radak: This is Makor (infinitive), as if it says A'amideha. Once the meat will be finished and the bones will burn, the pot will be empty on the fire.
Malbim: After it will be empty from meat and water (all the soldiers will die), the pot will stand on the coals below, which are from "Dur ha'Atzamim Tachteha" (5; the bones arranged underneath it).
What is "Lema'an Techam"?
Radak: This is Nif'al conjugation; the root is Chamah. The Mashal is, after the city will be empty of its people, it will be desolate - "Gafris va'Melach Sereifah Chol Artzah" (Devarim 29:22).
Why does it say "v'Charah Nechushtah"?
Radak: The root is Charar, like I explained "Yecharu" (10). Nechushtah is the bottom of the pot. [Since the pot will be empty on the fire], its bottom will burn. A Mishnah (Kelim 8:3) says, if a barrel full of Tahor liquids was placed under Nechushto (the bottom) of an oven...
Malbim: This is a Mashal for breaching the wall.
How will the Tum'ah be melted in it?
Radak: It will be absorbed in the earthenware of the pot.
What is the meaning of "Titum Chel'asah"?
Rashi: The filth will be finished and absorbed into the pot, which is of copper.
Radak: The matter is repeated in different words (the filth will be absorbed into the pot). Titum has a Shuruk in place of a Cholem, like "v'Sifsei Chachamim Tishmurem" (Mishlei 14:3).
Malbim: They will receive the punishment for their sins and be purified from them; also, the Resha'im will die.