A fire broke out in a 29th floor unit of a block at The Pinnacle@Duxton on Cantonment Road on Sunday afternoon.
A resident in the flat next door in Block 1E said she heard loud pops and smelt smoke around 3.35pm.
Mrs Tang Sock Hoon, an administrator in her 40s, said she was doing her laundry when she heard the sound.
"It was like firecrackers - pop, pop. I saw black smoke coming out from their kitchen, and it smelt quite strong."
She left the building with her father-in-law and daughter, who called the Singapore Civil Defence Force.
Smoke was seen coming from the upper levels of the affected block, and curious onlookers were peering up at the building.
A resident said she initially thought it was haze, before the fire alarm went off, and two fire trucks and the police arrived at the scene.
The residents of the five-room unit that caught fire, a couple in their 30s with a son in primary school, declined to be named, but the man said he had been out when the fire started with his wife and son asleep in a bedroom.
It was the child who had noticed the smoke and woken his mother.
It was likely that an altar candle had tipped over, the man added. No one was injured, but he said: "The whole living room is gone."
The Pinnacle, an iconic public housing development, comprises seven connected 50-storey towers. It was completed in December 2009.