The online dictionaries say that boondocks is from Tagalog bundok, meaning mountain.

I had heard–I guess it is a false etymology–that boondocks was named after shipping docks built outside of town. They were called boon because it was less expensive to moor there. Hence, boondocks came to mean “out of town.” That etymology made sense in Michigan, where a lot of slang came from the Great Lakes shipping industry.

Thus, whenever I said, “out in the boonies,” to you, I thought I was teaching you Michigan slang.