Possible Clues:

• A South American city so songlike
• Oratorio passage
• Short melodic solo
• Vocal performance in opera included by impresario sometimes
• Certain ''Magic Flute'' solo
• Lyrical piece a Portuguese-speaking city thus presented
• Aria? No, but it's melodic
• A funny person finishing early with extremely operatic piece?
• Melodic, musically
• Recitative song