Welcome at HCM.
Walking on operated knee is indicated after sufficient healing of bone & with strength in patient.You should use walker ,as with it there is partial loading over the knee.
Pop sensation may be due to injury
& presence of swelling at cartilage
over the knee.
Burning sensation is a part of healing process which may be there due to increase circulation or stimulation with growth factors.
You should keep your knee in position as advised by your operating doctor,as he is the best person who know about status of your knee bones.
Hope this will help you.