Ratboys opens its new album, Singin’ to an Empty Chair, with an invitation. “What’s it gonna take to open up this time?” vocalist Julia Steiner sings, launching an 11-song conversation that stands as Ratboys’ most introspective and emotionally driven work yet. Before long, the song swells into the sort of musical sunshower that’s become Ratboys’ specialty, underscoring the high stakes across the band’s sixth album and how gracefully the four-piece navigates them. When Steiner asks the question on “Open Up,” it’s clear she really means it.