You Do Need power plug adapter while traveling from Bulgaria to Laos.

Here is Why You Need An Adapter

The outlet and plug type used in Laos are A, B, C, E and F and in Bulgaria are C and F. This is how they look like.

Bulgaria

In Bulgaria, outlets of type C and F are in use.

Type C

Type F

Laos

In Laos, outlets of type A, B, C, E and F are in use.

Type A

Type B

Type C

Type E

Type F