Oh dear, all the time! Just a few that I remember...
La Cage aux Folles: The last time I saw/heard/felt/experienced Philip Quast singing "Song on the Sand". And then a bit during the curtain call.
Avenue Q: Julie Atherton singing "There's a Fine, Fine Line". I was a bit drunk, OK!
A Streetcar Named Desire: I can't even *read* the scene where Blanche is telling Mitch about her husband without getting emotional.
War Horse: When adult Joey comes on for the first time, and again at the end. And maybe a few other times. JOEEEEEEEEEEEEEYYYYYYYYY!!!!!!!!!
The Habit of Art: Wasn't expecting it at all. Last performance, Richard Griffiths doing the Auden poem. Not proper crying, but I got a bit choked up...
The History Boys: The Drummer Hodge bit, if it's done well. Most recently Gerard Murphy did it brilliantly in the UK tour. Also Hector's final speech. In the film, "Bye Bye Blackbird" always gets to me, though it didn't really in the last stage production I saw.
It wasn't a production of the play as such, but Simon Callow doing Lear's "I am a very foolish fond old man" was startlingly moving. Looking forward to Derek Jacobi's take on it later in the year.
I often get a bit choked up as the curtain comes down and/or during the curtain call, when I know I've seen something special.
A View from the Bridge,
Arcadia,
After the Dance and
All My Sons were recent ones, where the emotions just really hit me after it had finished.
Given how fabulously well-done
Part 1 was, I will be very disappointed if I don't at least come close to tears at some point in
Henry IV Part 2 at the Globe in a few weeks, since there are parts of it that really get to me just reading it. "I know thee not, old man."