Thanks, mcvl! It is reassuring to know I am not alone. Since I posted my question, I found another description that included "popcorn, lemongrass and roasted nuts" and that does get closer (and sounds nicer than hot asphalt or even leather boot, inside or out). As Ii was walking through the coffee aisle at the store today, I thought there was some component of the aroma of darkly roasted coffee beans in the curry leaf smell, too.
When you say you have had zero luck freezing them, what has happened to them? I used two sprigs the other day and froze the leaves of a third, and planned to buy more and freeze them the next time I could find them.