In A Raisin in the Sun, what does the casual chat between Ruth and George Murchinson when Ruth refers to the bombings reveal about Ruth's awareness of racial tensions?

Ruth, in my opinion, is one of the most interesting characters in Lorraine Hansberry's A Raisin in the Sun. She comes off as a simple woman but is quite astute. It often seems that she's holding back her intelligence to ensure that her husband, Walter Lee, always feels good about himself. She lacks the formal education and pretensions of her sister-in-law, Beneatha. She shares Lena Younger's reliance on common sense and dedication to family; however, Ruth is practical and less content to endure things as they are, a sentiment that rises within her when, after Walter loses a chunk of the insurance money, she promises to scrub every kitchen in Chicago to ensure that her family will get out of the cramped kitchenette in which they live.
Ruth's awareness comes to the fore during a "casual conversation" with George Murchison about the weather. He's there to meet Beneatha for a date. Ruth invites him to sit and remarks on how warm it is in Chicago, for September. Then, she says:

Everybody say it's got to do with them bombs and things they keep setting off. (Pause.) Would you like a nice cold beer?

Hansberry may have been using Ruth to refer to any number of bombings that occurred in the 1950s, carried out against both black people and Jewish people. Those bombings would continue to the end of the decade and mark the next one, most notably with the bombing of a Birmingham church, which killed four little choir girls. The comment is both timely and prescient. The reference to unusually rising heat seems to anticipate the rising tensions that will come to a head in the next decade.
Hansberry probably wanted to convey that Ruth, as a member of the race affected by these incidents, would likely be aware of them. However, Hansberry uses all of her characters as mouthpieces to express particular political ideas and perspectives.