The bug
If a block is destroyed due to a missing support block (e.g. the block that a torch is attached to is destroyed), said block will play breaking sound and particles despite you not breaking it directly. This seems to affect all blocks except for rails.
In versions 17w46a and prior, the only blocks that do this are chorus fruit and cacti; other blocks such as torches, stairs and grass would simply disappear.
How to reproduce
Linked issues
is duplicated by 3
relates to 3
Comments 7

Can confirm. Simillar bugs / issues - MC-122263
Could this be intentional? It's a cool effect imho and already happens on Bedrock edition.
I can't find a single instance of this happening on Bedrock edition, even cactus. Chorus fruit does, but for a different reason.
It makes nether portals quite interesting: https://gfycat.com/FirmFineAdouri

On Bedrock edition (Windows 10) it only seems to be happening with double blocks except cactus (doors, double tallgrass etc). (Reported this as MCPE-29266)
Ah, got it. Figures that I didn't test any of those, haha. Thanks!
I just found that this bug causes piston heads to make the breaking sound if a powered piston is broken in 1.13-pre7. I feel a sound should only play if a block is destroyed AND the corresponding item drops.
This is possibly related to MC-122228, which describes double chests playing their opening/closing sounds twice.