It's pretty simple. You only need to focus on the reasons why people are homeless. Do they have good education? do they get better job? Or do they find ways inorder not to be homeless? Questions like that will help you determine why? and what can be the solutions inorder for them not to be homeless.
He uses figurative language by comparing injustice to a boiling pot. This is so the people he is talking to get a better/ complete picture of what is happening.