you could try blowing out your white background by setting your speedlight off-camera in such a way that it is aimed at the background. Use the on-camera flash to light the drop, and the off-camera speedlight to make the background white!
By “off-camera” I mean literally taking it off the camera. 🙂
Your speedlight should have come with a small “shoe” that you can mount your flash on, to set it on a table, or even screw it onto a tripod!
(You’ll have to set your flash to “Slave Mode” [S1] to make it work off-camera.)