Yes, boiling brake fluid. It is the only explanation. Source of the boiling is usually a dragging front caliper, where both circuits appear. Age and contamination of brake fluid is an exacerbating factor. But the exhaust leak bears looking into for both the obvious reason and its possible relationship to the brake lines.

The exit ramp (or toll booth) is where this usually happens with a dragging front caliper. A good diagnosis can be made using the back of the hand as an impromptu IR thermometer, holding it near the wheel hubs immediately after doing some high speed driving.
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Art Benstein near Baltimore

If you tell the truth, you don't have to remember anything.