Balsam fir.

I take my current crop of students to the local arboretum every year.

Not local to here, but local to where I teach a week every summer.

Mustila arboretum sports quite a few exotics, including a few balsam firs (Abies balsamea). Some of which are young enough to still have bark bubbles with liquid resin in them. And I demonstrate the popping of those bubbles to my students, every year. You can squirt the very liquid resin a couple of meters (or yards), if you pop the bubbles right.

Usually, I try not to hit students, but I get hit myself every year, cos the tree has a sense of humor, too. I think.

This year I got some of the resin on my glasses (try to wipe that off. Heh. A tincture did the trick.), on one of my eyelids (it's sorta kinda difficult to blink when your eyelid gets almost-glued open all the time) (the tincture helped some, and time took care of the rest), and on my lips, which thus were almost-glued shut until I used some tincture on that, too. Heh.

And I got some resin on my clothes, of course. Which doesn't matter, cos a) they've invented washing machines, and b) that's my outdoor clothes anyway.

Then I let the others pop some bubbles, too. Lotsa fun!