The song "Samson" is Regina Spektor’s "Freebird."

Fans called out for it constantly during her show Saturday night at the Riverside Theater. At first it was endearing. Then it got downright demanding.

"Hey! Regina! Samson! Sam. Sonnnnn."

Well, good things come to those who wait: Spektor closed out the show with the powerful ballad off her fantastic 2006 album "Begin to Hope" and the crowd sang along.

But who knows why they were being so demanding – nearly every song Spektor played this evening was warmly met by an audience that clearly knows and loves the piano-pop chanteuse. It was the largest and most enthusiastic crowd I’ve seen since Summerfest. I’d wager that even the Bieber Fever-stricken tweens who will rock the BMO Harris Bradley Center to its foundation Sunday night don’t have anything on Spektor’s throngs of loyal and adoring fans.

Spektor’s dynamic piano-playing punched up her quirky songs; she pulled her own musical weight and rarely got up from the piano, although she was accompanied by a cellist, drummer and keyboardist.

The Russian immigrant is proud of her roots and many of her songs contain references to her homeland. She was born in Moscow and emigrated with her family in 1989 (kudos, perestroika). Her nationality was proudly on display tonight. She performed "The Prayer of Francois Villon (Molitva)" by Serbian singer Marija Serifovic to great acclaim (a member of the audience called out to her in Russian and she answered in kind).

The classical influences of her early years as a piano prodigy are evident in songs like "Oh Marcello" (from her latest album, "What We Saw From the Cheap Seats") and "Blue Lips," a delightfully subverted hipster ballad.

If there is one complaint to be lodged against Spektor, it’s that she sometimes gives in to the mellowness of her own sound. Her anti-folk vibe often threatens to transform into coffeehouse music. She is to be commended for employing an impressive arsenal of unconventional tricks to keep that from happening – including voice distortion, glottal stops and even a dash of beatboxing in "Dance Anthem of the ‘80s."

But what she really has going for her is raw talent. Hers is a caliber of voice that is unique in its strength and range, and she’s one of the few singers who actually sounds better in person than she does on her recorded tracks. Pair that with her stirring piano melodies and edgy songwriting, and it’s safe to say this girl will keep her music off of commercials for Apple products. Her powerful collaboration with opening act Only Son on their co-written song "Call Them Brothers" is proof of that.

"I have to share with you two words that have become very important to me, and that I’m going to miss when I go back to New York tomorrow," she said, in what was a rare moment of conversational interaction with the crowd. "Cheese curds. I love that sh*t."

She also gets brownie points for winning over her audience even without giving into their clamoring for "Samson." Enthusiasm was high for every tune; the crowd sang and clapped along to "Firewood" almost as much as they did to "Fidelity" (one of Spektor’s more mainstream hits).

A truly moving moment was when she played "Ballad of a Politician." From her latest album, this song is a subtle commentary on the American dream, powerfully written and performed by an immigrant who knows of what she speaks.