Connie Francis' friend tells PEOPLE about the final days before her death, saying she'd be 'smiling' knowing she 'left this world as big a star' as ever

From 1958 to 1964, she was the most popular female singer in the United States, selling 40 million records with tunes like “Who’s Sorry Now” and “Where the Boys Are.”

American singer, who has died at age 87, is largely known for her resonant pop hits such as ‘Pretty Little Baby,’ but her unique talent is best heard in the many albums she recorded in international dialects.