Steps to reproduce

1. Place a boat on land.
2. Enter the boat.
3. Exit the boat.
4. Place a campfire.
5. About 5 blocks away from the campfire, place a boat facing toward the campfire.
6. Enter the boat and slowly move toward the campfire.
7. Place a boat on land.
8. Enter the boat.
9. Try to place blocks a few blocks in front you.

Expected results

In step (3) the boat stays still. In step (6) nothing happens. In step (9) you place the blocks.

Observed results

In step (3) the boat launches forward by several blocks. In step (6) the boat catches fire and gets destroyed by the campfire while several blocks away. In step (9) you cannot place the blocks, or they place briefly then disappear and remain in your inventory.

This is happening on any boats, especially boat with chest. The boat is supposed to stay on the same positon instead of randomly teleported. It depends how far you look at the ground before leave the boat.

Sometimes it fixes itself if you left and go back to your world or maybe restart minecraft.