Water droplet on the edge of a leaf –

The house plant Philodendron White Measure has, on occasion, shed a few tears. Right-hand picture is a close-up of the same leaf shown in left-hand pic.

Update 10/10/2021.
This is known as ‘guttation’.
Here’s the definition :-

gut·​ta·​tion |  \ ˌgə-ˈtā-shən   \

Definition of guttation

the exudation of liquid water from the uninjured surface of a plant leaf