Pulis travelled back from Newport after spending the day with family following the death of his mother earlier in the day and arrived just after kick-off.
However, he did not take his place on the touchline until the second half, when his side were already losing, but witnessed a character-filled comeback with an injury-time winner from Robert Huth.
"I knew he was going to get here at some time but I didn't know when because he travelled up from south Wales," said Kemp.
"But I knew during the first half he was here because he was phoning down to the bench.
"He has obviously had a very sad day but typically for him he wanted to get straight into it, put his overalls on and get on with his work.
"That is why he has been a great manager for this football club. He is desperate, with all else he has got going on, to have an impact.
"His appearance gave the players and the fans a boost and I think you saw that."
Kemp said that despite Pulis' personal tragedy he did not hold back in his criticism of the players during the interval.
"He was in the dressing room for the half-time team-talk and he took the paint off the walls," he added.
"The result's not going to change what has happened to him today but hopefully it will give him a boost that the team is up and running and got three points."
Huth deflected home Matt Etherington's shot in the third minute of injury time to snatch a first victory of the season.
Stewart Downing's 35th-minute diving header had put Villa ahead but £8million club-record signing Kenwyne Jones equalised with 10 minutes to go of his home debut.
And there was even later drama as Huth capitalised on a scramble in the penalty area from substitute Jermaine Pennant's free-kick.
Etherington claimed the appearance of Pulis on the sidelines inspired the players.
"Obviously he wasn't happy at half-time, he was very disappointed about what was happening," he told Sky Sports.
""He had thought it would be too much to be with us but after the first half and the way we played he came in.
"They were on top and he wasn't happy, so he came in and I think we were better in the second half."
Aston Villa caretaker manager Kevin Macdonald also paid tribute to Pulis' strength of character.
"I feel very sad for Tony but he is a wonderful man. I don't think it would have changed the way his team played," he said.
"I think the way they acknowledge how good he is to them showed in the first half as well."
On the result he added: "We're very disappointed in the result but we know that happens in football."