Why does it say "Lachen"?
Radak: Now it explains the Mashal. Ir ha'Damim, Yerushalayim, is the pot.
What is "Chel'asah"?
Rashi: It is the filth (froth) that they take off the pot's mouth via boiling
Why does it say "v'Chel'asah Lo Yatz'ah Mimenah"?
Rashi: The Resha'im in it did not leave.
Radak: The sins seen in it, which are repulsive like filth to all who see it [did not depart].
Malbim: It is full of filth; only the filth did not leave.
What is "li'Nsacheha li'Nsacheha"?
Rashi: Galus after Galus; individuals go out and fall to the Kasdim.
Radak: Do not take out of it the pieces at once, rather, pieces after pieces. This is a Mashal - residents of Yerushalayim and those who gathered into it, will not be eradicated at once. Rather, soldiers will leave and be killed, and later others leave and are killed. And so they were exiled, Galus after Galus - first Galus Yehoyachin, and afterwards Galus of the Churban and Tzidkiyah.
Malbim: The good pieces will not remain. They were removed one after the other - many of the good ones were killed, and many fell [captive] to the Kasdim.
What Goral did not come upon her?
Rashi: This is unlike pots that they take out their pieces together, to put each person's portion in front of him.
Rashi citing Targum Yonasan: Since they did not repent, Hashem's portion did not fall on them 1 .
Radak: There was no lottery which piece will come out first. Rather, whichever happened [to be on top, came out first]. The Nimshal is, there was no lottery on Yoshevei Yerushalayim. Some happened to be taken captive, some died via plague, and some via hunger.
Malbim citing the Meforshim: This is unlike a pot in which meat cooked. They remove the meat and divide the pieces via lottery to each person. Here, each left via chance.
Malbim: This is said in astonishment. Did Nebuchadnetzar's lottery [which way to go] not fall on [Yerushalayim], and not on Rabas Bnei Amon? This was via Hashem, to destroy it.
I.e. He did not choose them for His portion. (PF)