What I expected to happen was to be able to see the Ender Crystal beam that hits the Ender Dragon when looking at the Ender Crystal and not having the Dragon in view.
What actually happened was that the beam did not appear.
Steps to Reproduce:
1. Stand on top of an obsidian tower facing the Ender Crystal.
2. Make sure that the Ender Dragon is facing the back of your player
(It happens in all gamemodes and if the Ender Dragon has {NoAI:1b} or {NoAI:0b}
Linked issues
Comments

Confirmed for 15w44b
Confirmed for 15w49b
Confirmed for 15w50a
Confirmed for 15w51a and 15w51b
Confirmed for 16w02a
Confirmed for 16w03a
Confirmed for 16w04a
Confirmed for 16w05a
Confirmed for 16w05b
Confirmed for 16w06a
Confirmed for 16w07a
Confirmed for 16w07b
Confirmed for 1.9 Pre-Release 1
Confirmed for 1.9 Pre-Release 2
Confirmed for 1.9 Pre-Release 3
Confirmed for 1.9 Pre-Release 4
Confirmed for 1.9.1 Pre-Release 1

changed the reported to @unknown as @unknown didn't keep the affected versions up-to-date
Thanks, @unknown! I'll keep it updated.
Confirmed for
15w36c
Rather change the title to "EnderCrystal beam not appearing when EnderDragon out of view"