Palatalization
During the palatalization of most hard consonants (the bilabial, labiodental and alveolar ones), the middle part of the tongue is lifted towards the palatum, resulting in the formation of a second articulatory centre whereby the specific palatal "clang" of the soft consonants is achieved. The articulation of alveolars /l/, /n/ and /r/, however, usually does not follow that rule; the palatal clang is achieved by moving the place of articulation further back towards the palatum so that /ʎ/, /ɲ/ and /rʲ/ are actually alveopalatal (postalvelolar) consonants. Soft /ɡ/ and /k/ (/ɡʲ/ and /kʲ/, respectively) are articulated not on the velum but on the palatum and are considered palatal consonants.
Read more about this topic: Bulgarski, Phonology, Consonants