The old Hemingway adage about the iceberg is still a good one. The right, really salient detail can hint/suggest at tons of stuff that doesn't have to be be poured directly into the novel.
This happens all the time in poetry where the part does stand for the whole and the precise word does the work of many worker bee words.
And, of course, there is always the surgical approach -- if the back story info takes a page, cut it by at least 1/2. Rent a chain saw if you have to. Such a wonderfully brutal tool.