"Wherefore say unto the children of Israel: I am the LORD, and I will bring you out from under the burdens of the Egyptians, and I will deliver you from their bondage, and I will redeem you with an outstretched arm, and with great judgments." We normally translate the verse to say that Hashem saved the Israelites from the סִבְלֹת of Egypt as the "burdens" of Egypt.
However, the verb לסבל can also mean " to tolerate, to put up with, to have patience for."
The S'fas Emes, second Grand Rabbi of Ger, says that the problem of the Israelites was that, prior to their enslavement, they had gotten comfortable with their lives in Egypt. They did not find the impurity and avodah zara of Egypt to be an intolerable abomination for them.