Most droprates are completely random, and have no memory of previous kills. Long dry streaks are possible, but the longer the less likely.
Some bosses do have some bad luck mitigation with slowly increasing droprates (with a max limit) after a certain amount of "dry" kills. I believe this is mostly for lore drops that are required for some completionist capes.
Kings Eastwood in
THE
GLOOP
, THE
BWIAN
, and THE
WIKI
music by Trewavio Morricone